Cylindrical heat exchanger with tube banks



Jam 23, 1962 R. F, cAUGl-HLL ETAL 3,018,089

CYLINDRICAL HEAT EXCHANGER WITH TUBE BANKS Filed oct. 3o, 195e 5 sheets-sheet 1 O d l 5 rra/Mfr v Jam 23, 1962 R. F. cAUGHlLL ETAL 3,018,089

CYLINDRICAL HEAT EXCHANGER WITH TUBE BANKS Filed Oct. 50. 1958 5 Sheets-Sheet 2 1 rra/may Jam 23, 1962 R. F. cAUGHlLL ETAL 3,018,089

CYLINDRICAL HEAT EXCHANGER WITH TUBE BANKS Filed Oct. 30, 1958 5 Sheets-Sheet 3 Armin/fr United States Patent O t 3,018,089 CYLINDRICAL HEAT EXCHAWGER WITH TUBE BANK Robert F. Canghill and Frank A. Disinger, Lockport,

NX., assignnrs to General Motors Corporation, Detroit, Micin, a corporation of Delaware Filed Ust. 36, 1958, Ser. No. 771,708 Claims. (Cl. 257-235) This invention relates to heat exchangers and more particularly to cylindrical heat exchangers having tubes for conducting one liuid and arranged in multiple banks adapted to traverse the path of a second fluid.

It is, of course, well known that heat exchangers for transferring heat from one fluid to another are subject to expansion and contraction diflieulties and that the latter are more pronounced as extreme differential temperatures are encountered. In order to minimize these diiculties, attempts have heretofore been made to design heat exchangers with a degree of freedom of movement for the parts thereby to lessen the strain on the metal. These attempts have not proceeded sumciently or with adequate success in many situations and particularly wherein high temperatures are encountered and are necessarily accompanied by considerable and often rapidly uctuating expansion or contraction of tubes, headers and supports.

An object of the present invention is to provide an improved heat exchanger with tubes for conducting one iiuid and forming a grille affording uniform distribution passages for the flow of a second fluid during heat exchange of the latter with the one liuid, and the over-all exchanger being characterized by temperature equalization in its parts and a minimum of metal strain due to expansion and contraction.

To this end, a feature of the present invention is a cylindrical heat exchanger in a casing formed to serve as a conduit, the exchanger utilizing multiple banks of tubes forming a grille traversing the conduit, each bank including relatively long intermediate headers each connected to a short inlet header and a short outlet header. Another feature comprises a heat exchanger with spaced groups of short inlet headers, spaced groups of short outlet headers, spaced groups of intermediate long headers and banks of tubes each connecting one of said groups of headers to one of the other groups of headers.

These and other important features of the invention will now be described in detail in the specification and then pointed out more particularly in the appended claims.

In the drawings:

FIG, l is a view in cross section looking in the direction of the arrows 1-1 in FIG. 2 and showing one embodiment of the present invention;

FIG. 2 is an elevation view of the heat exchanger shown in FIG. 1, an outside casing being in section and portions being broken away to facilitate illustration;

FIG. 3 is an enlarged View taken in cross section and showing two of the headers depicted in FIG. 1; and

FIG. 4 is a sectional view looking in the direction of the arrows 4-4 in FIG. 3.

In a heat exchanger of the type specifically illustrated, it is desirable to transfer heat from a rapidly owing stream of fluid such as air to a more strictly conned flowing stream such as liquid. In the present instance the air is conducted along a given and generally linear path by means of a casing itl which is in the form of a two-part open ended conduit of cylindrical contour. A second conduit 12 of smaller diameter is coaxially arranged within the casing 1@ and may serve as a support for the heat exchanger or for some other purpose. The tube 12 is preferably free of the heat exchanger to promote best expansion characteristics and such construction is disclosed in the drawings. The air stream is confined to the ltig@ Patented Jan'. 23, 1962 lCC annular space between the two casings 10 and 12 and for counter-current eifect the general direction of the ailn movement is from left to right as viewed in FIG. 2.

Within the contines of the casing l@ and spaced along the length of the inside wall thereof are two annular ducts 14 and 16. The duct 14 is herein illustrated as an inlet duct and is provided with a radial inlet branch 18 which extends outwardly through the casing 10. The annular duct 16 is similarly provided with a branch Ztl which, in this case, is adapted to serve as an outlet connection.

Three groups of short inlet headers 22 are connected at spaced portions of the inlet duct 14. There are four inlet headers 22 in each group. Connected to spaced portions of the outlet duct 16 are three groups of short outlet headers 24. Between each group of headers 22 and a group of outlet headers 24 is arranged a group of intermediate long headers 26. There are four headers 26 in each group and it will be noted that the inlet and outlet headers 22 and 24 each span only about half the distance between the ducts 14 and 16 whereas each of the long intermediate headers 26 spans substantially the full distance between those ducts.

- Each long intermediate header 26 is connected to a short header 22 or 24 by a bank of tubes generally indicated at 30 or 32. The joinder of these tubes to a given header is exemplified in FIG. 3 and shows how the tubes are arranged and bent for connection to a header 24. It will be noted that each tube has an intermediate and arcuate length portion 31 or 33 extending coaxially with the exchanger. It should also be noted that portions of each tube extend inwardly from a header and, after extending in an arc, they extend outwardly for connection with a header 24. The direction of tiuid flow in all the tubes is counterclockwise as viewed in FIG. 1. Each bank of tubes passes by a group of inlet or outlet headers 22 or 24 and is connected to one-half of a group of intermediate headers 26. A mounting plate itl in the form of a ring is interposed between the two parts of the casing itl. This plate is welded to the casing halves and also to the inlet, outlet and intermediate headers.

The bending of the tubes, as illustrated, minimizes the effect of thermal expansion and contraction for each tube may move freely without support from rigid members. The speciic nature of the support of the heat exchanger within the casing 10 may vary considerably. The annular ducts 14 and 16 may be attached to the inside wall of the casing 10 as the sole means of support for the heat eX- changer and this permits a maximum freedom of motion for the long and short headers as well as for the tubes themselves. The grille formed by the tubes transverse to the casing 10 results in a uniform distribution of air as the latter Hows through and temperature equalization is partially brought about through the unit structure because of the action of the grille on the air. The staggering of the streams of liquid by the arrangement of the tubes and the criss-crossing of these tubes in the grille further promotes the equilization of temperature.

In order further to promote the heat transfer from the fluid in the tubes to the fluid flowing through the casing 10, or vice Versa depending upon the particular application, the tubes are provided with fins 36 joined in spaced relation along the length of each tube. These tins are fixed in position by brazing or by mere driving tit. The tubes criss-cross in traversing the passage through the casing 10 but this does not prevent the use of the iins 36 as the criss-crossing tubes are in banks which lie in different planes as shown in FIG. 2 and the ns of one tube are clear of the fins of adjacent tubes in the same bank. The tins, being in the form of discs, are spaced from each other as seen iu FIG. 3, and they lie in planes extending in the general direction of the passage formed by the casing 10 to present a minimum of resistance to ow along that passage. It follows that ns 36 may be located along substantially the full length of each tube.

We claim:

1. A cylindrical heat exchanger comprising a casing in the form of a conduit, Vsaid exchanger including an annular inlet duct and an annular outlet duct, said ducts lying in spaced planes extending transverse to the axis of said casing, multiple banks of tubes forming a grill across a substantial portion of the space extending between said planes, spaced groups of short inlet headers connected to said inlet duct, spaced groups of short outlet headers connected to said outlet duct, spaced groups of long intermediate headers arranged parallel with said inlet and outlet headers and terminating short of said annular ducts, said inlet and outlet headers in each of their respective groups being sequentially arranged along the lengths of the said inlet and outlet ducts, each group of short inlet headers communicating with a group of said long intermediate headers by means of one of said banks of tubes, and said long intermediate headers communicating with a group of said short outlet headers by another of said banks of tubes.

2. A cylindrical heat exchanger comprising a casing in the form of a conduit, said exchanger including an annular inlet duct and an annular outlet duct lying in planes extending transverse to the axis of said casing, multiple banks of tubes forming a grill across a substantial portion of the space extending between the said planes, spaced groups ot short inlet headers connected to said inlet duct, spaced groups of short outlet headers connected to said outlet duct, spaced groups of long intermediate headers arranged parallel with said inlet and outlet headers and having their ends free of said ducts, two of said banks of tubes being arranged in series with a group of said long intermediate headers cooperatively to connect the inlet duct by way of a group of short inlet headers to a group of short outlet headers and the outlet duct, and each of said tubes extending inwardly with respect to the casing from one of said headers and then partially around the axis of the casing and then outwardly with respect to the casing to one of the other headers.

3. A heat exchanger comprising a casing in the form of an open-ended conduit dening a ilow passage, tWo ducts extending around the interior of said casing, a group of short headers connected to each one of said ducts and terminating short of the other of said ducts, intermediate headers interposed between and spaced from said ducts, said short and intermediate headers being parallel and arranged at the same radial distance from the axis of said tlow passage, and tubes forming a grill across said flow passage and cooperating with said intermediate headers in connecting said groups of short headers.

4. A heat exchanger comprising a casing dening a ow passage, two ducts in planes extending transverse to the interior of said casing, multiple groups of short headers connected to each of said ducts and terminating short of the other, multiple groups of intermediate headers spaced from said ducts, said short and intermediate headers being arranged in parallel and normal to said planes, and tubes arranged in banks extending into said flow passage and connecting the short headers of one duct to those of the other by Way of said intermediate headers,

5. A heat exchanger such as set forth in claim 4, heat exchange ns mounted along each of said tubes, and each of said fins being in spaced relation with adjacent ns and lying in a plane extending in the direction of the said flow passage.

References Cited in the le of this patent UNITED STATES PATENTS 39,709 Babbitt Sept. 1, 1863 1,884,778 Lucke et al. Oct. 25, 1932 2,033,077 Kerr et al. Mar. 3, 1936 2,739,795 Mueller Mar. 27, 1956 FOREIGN PATENTS 493,768 Belgium Feb. 28, 1950 

